Fluid operated multi-stage machine



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FLUID OPERATED MULTI-STAGE MACHINE Filed April 20, 1965 2 SheetsSheet l Inuenlors @Ewmmfi E FQE DEEWBCkQ AWMUE5$ Mmamum HENRY Mmwmmmm W as fawn met A ftorrmy S 9 W67 G. F. ARKLES$ ETAL P SQ FLUID OPERATED MULTI-STAGE MACHINE 2 Sheets-Sheet 2 Filed April 20, 1965 United States Patent C) 3,296,972 FLUID OPERATED MULTI-STAGE MACHINE George Frederick Arkless and Harold Henry Anderson, both of Cathcart, Glasgow, Scotland, assignors to G. & J. Weir Limited Filed Apr. 20, 1965, Ser. No. 449,452 Claims priority, application Great Britain, June 4, 1964, 23,120/64 7 Claims. (Cl. 103-103) This invention relates to improvements in a fluid operated multi-stage machine, intended to operate as a pump or a turbine.

According to the present invention there is provided a fluid operated multi-stage machine including a rotatable shaft, -a casing, a fluid impeller within said casing and rotatable with said shaft, the impeller having a peripheral ring of vanes concentric with the shaft, adjacent vanes defining fluid passes, a plurality of diffuser passages in the casing and spaced around the outer periphery of the impeller vanes, each diffuser passage communicating at one end with the outer ends of a number of fluid passes, and the v-anes serving to seal adjacent diffuser passages from one another, a number of return passages being provided to enable fluid communication between the other end of each diffuser passage and the inner ends of the fluid passes which are in communication with the next successive diffuser passage, and fluid inlet and outlet passages into and out of said casing, said inlet passage communicating with the fluid passes in communication with the first stage diffuser and said outlet passage communicating with the diffuser of the last stage when the machine is operating as a pump.

Preferably, the impeller is provided with shroud plates to form the sides of the fluid passes.

Preferably, at least one of the shroud plates is removably attached to the impeller.

Preferably, the casing is provided with annular rings of a soft material, the rings being co-axial with the shroud plates and abutting the shroud plates.

Preferably, the part of the casing separating the diffuser passage of the last stage from the diffuser passage of the first stage and the part of the casing separating the return passage of the last stage from the inlet passage to the first stage are provided with a plurality of separate axially extending grooves.

Preferably, the shaft rigidity is such as to avoid any rubbing contact between rotating and stationary parts.

Preferably, when the machine is acting as a pump the inlet passage is co-axial with the shaft and an axial flow impeller is provided in this passage to impose the necessary inlet pressure on the fluid.

One embodiment of the present invention will now be described merely by way of example with reference to the accompanying drawings in which:

FIG. 1 is a sectional end elevation of the fluid operated multi-stage machine, and

FIG. 2 is a sectional front elevation of the fluid operated multi-stage machine.

- In the embodiment the multi-stage fluid operated machine is acting as a pump.

A centrifugal impeller 10, mounted rigidly on a shaft 11, is rotatable in a clockwise direction with said shaft within a casing 12, said impeller having a peripheral ring of vanes 13 concentric with the shaft, adjacent vanes defining fluid passes.

A plurality of diffuser passages 14, in the casing 12, are spaced around the outer periphery of the impeller vanes 13, each diffuser passage communicating at one end with the outer end of a group of fluid passes, and at the other end with a return pass-age 15 which communicates Ice with the inner ends of the fluid passes which are in communication with the next successive diffuser passage.

The extreme vanes of each group of fluid passes serve as pressure walls, sealing adjacent diffuser passages from one another.

The casing 12 is provided with an inlet 16 and an outlet passage 17, said inlet passage supplying fluid to the fluid passes in communication with the first stage diffuser and said outlet passage communicating with the diffuser of the last stage.

The impeller is provided with shroud plates 18, 19 which formuthe sides of the fluid passes. One of the shroud plates 19 is removably attached to the impeller 10 to facilitate assembly and to enable the performance of the pump to be adjusted by varying the width of the impeller being used in the machine. The detachable shroud plate 19 is provided with small vanes 20 which ensure that said detachable shroud plate is concentric and in line with the vanes of the impeller 10.

Annular rings 21, of a soft material, are attached to the casing 12 such that they are concentric with the shroud plates 18, 19 and abut the shroud plates, losses of higher pressure fluid passing into regions of lower pressure are thus mitigated.

The parts of the casing 12 separating the diffuser passages of the first and last stages, and the inlet to the first stage and return passage of the last stage are provided with a plurality of axially extending grooves 22 which cause turbulence in any fluid attempting to leak from the last stage to the first stage and thus minimises any leakage.

The shaft 11 on which the impeller 10 is attached is of relatively large thickness and short length and the clearance 23 between the shaft 11 and the casing 12 is great enough, for example 20 thousandths of an inch, to permit the machine to be run dry without seizure, the pump can thus be self-primed. The clearance 23 between the shaft and the casing also allows air to be discharged to atmosphere during the priming period, and a suitable drain 24 is also provided to assist 'with this discharging.

The inlet 16 to the pump is coaxial with the shaft 11 and is provided with an axial flow impeller 25 to impose the necessary inlet pressure on the fluid entering the first stage.

A machine according to the present invention could generate a pressure defence at zero flow in order to serve as a gland and prevent leakage where a rotating shaft passes through the wall of a pressure vessel. The suction of the machine would be connected to the atmospheric side of the pressure vessel and the discharge of the machine would be connected to the interior of the pressure vessel. The machine will thus serve as a gland and obviate leakage from the pressure vessel along the shaft to the atmosphere.

In operation fluid entering the casing 12 is given an initial pressure rise by the axial flow impeller 25 in the inlet passage 16, this pressure rise being sufficient to cause the fluid to enter the fluid passes of the first stage of the rotating impeller 10.

The fluid is delivered from the fluid passes to the diffuser passage 14 of the first stage and flows to the fluid passes of the second stage through the first stage return passage 15. The fluid is then delivered by the impeller 10 to the second stage diffuser, and thence through the successive fluid passes and diffusers 14, until, at a greatly increased pressure, it reaches the diffuser passage of the last stage which communicates with the discharge passage 17 out of the casing 12.

In the turbine version of the machine the fluid flow is reversed and high pressure fluid is supplied to the diffuser passage of the last stage, the direction of rotation of the impeller in this case being anti-clockwise.

We claim:

1. A fluid operated multi-stage machine including a rotatable shaft, a casing, 21 fluid impeller within said casing and rotatable with said shaft, the impeller having vanes which, together with shroud plates define fluid passes, a plurality of diffuser passages in the casing and spaced around the periphery of the impeller vanes, each diffuser passage communicating at one end with the outer ends of a number of fluid passes, and the vanes serving to seal adjacent fluid passages from one another, a number of return passages being provided to enable fluid communication between the other end of each diffuser passage and the inner ends of the fluid passes which are in communication with the next successive diffuser passage, and fluid inlet and outlet passages into and out of said casing, said inlet passage communicating with the fluid passes in communication with the first stage diffuser and said outlet passage communicating with the diffuser of the last stage when the machine is operating as a pump, the impeller being overhung from the shaft and being annular, said return passages communicating with the inner periphery of the impeller, said diffusers with the outer periphery of the impeller.

2. A fluid operated multi-stage machine as claimed in claim 1 in which at least one of the shroud plates is removably attached to the impeller.

3. A fluid operated multi-stage machine as claimed in claim 1, in which the casing is provided with annular rings of a soft material, the rings being co-axial with the shroud plates and abutting the shroud plates.

4. A fluid operated multi-stage machine as claimed in claim 1, in which the part of the casing separating the diffuser passage of the last stage from the diffuser passage of the first stage is provided with a plurality of separate axially extending grooves.

5. A fluid operated multi-stage machine as claimed in claim 1 in which the part of the casing separating the return passage of the last stage from the inlet passage to the first stage is provided with a plurality of separate axially extending grooves.

6. A fluid operated multi-stage machine as claimed in claim 1 in which the shaft rigidity is such as to avoid any rubbing contact between rotating and stationary parts.

7. A fluid operated multi-stage machine as claimed in claim 1, in which the inlet passage is co-axial with the shaft and an axial flow impeller is provided in this passage to impose the necessary inlet pressure on the fluid when the machine is acting as a pump.

References Cited by the Examiner UNITED STATES PATENTS 2,120,277 6/1938 Grierson 103-114 2,496,496 2/1950 Roth et a1 103103 FOREIGN PATENTS 128,026 7/1948 Australia. 1,141,880 3/1957 France. I

537,727 7/ 1943 Great Britain. 108,042 8/ 1943 Sweden.

DONLEY .l. STOCKING, Primary Examiner.

HENRY F. RADUAZO, Examiner. 

1. A FLUID OPERATED MULTI-STAGE MACHINE INCLUDING A ROTATABLE SHAFT, A CASING, A FLUID IMPELLER WITHIN SAID CASING AND ROTATABLE WITH SAID SHAFT, THE IMPELLER HAVING VANES WHICH, TOGETHER WITH SHROUD PLATES DEFINE FLUID PASSES, A PLURALITY OF DIFFUSER PASSAGES IN THE CASING AND SPACED AROUND THE PERIPHERY OF THE IMPELLER VANES, EACH DIFFUSER PASSAGE COMMUNICATING AT ONE END WITH THE OUTER ENDS OF A NUMBER OF FLUID PASSAGES, AND THE VANES SERVING TO SEAL ADJACENT FLUID PASSAGES FROM ONE ANOTHER, A NUMBER OF RETURN PASSAGES BEING PROVIDED TO ENABLE FLUID COMMUNICATION BETWEEN THE OTHER END OF EACH DIFFUSER PASSAGE AND THE INNER ENDS OF THE FLUID PASSES WHICH ARE IN COMMUNICATION WITH THE NEXT SUCCESSIVE DIFFUSER PASSAGE, AND FLUID INLET AND OUTLET PASSAGES INTO AND OUT OF SAID CASING, SAID INLET PASSAGE COMMUNICATING WITH THE FLUID PASSES IN COMMUNICATION WITH THE FIRST STAGE DIFFUSER AND SAID OUTLET PASSAGE COMMUNICATING WITH THE DIFFUSER OF THE LAST STAGE WHEN THE MACHINE IS OPERATING AS A PUMP, THE IMPELLER BEING OVERHUNG FROM THE SHAFT 